The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Friction welding is a welding process in which the mechanical heat necessary for welding is generated by rubbing the parts to be joined against each other under an axial forging pressure.
Patent US 2003/0201305 A1 discloses a friction welding device for attaching blades to a rotor. The principle of welding disclosed in this document is based on linear friction and uses a device initially designed for linear welding that is capable of imparting a back and forth motion to a work piece relative to the substrate to which it is intended that it be welded. The movement of the work piece, i.e. the blade, is guided to define a curved path generally matching the cross-sectional profile of the blade. The purpose of the curved path is to avoid a part of the blade's contact surface with the rotor being exposed during friction and undergoing direct contact with the ambient air and uncontrolled cooling. This solution is therefore particularly suitable for highly curved blades. This process, however, requires heavy and expensive equipment, especially because of the use of linear friction welding. Indeed, reciprocating back and forth movements of the work piece are very restrictive, particularly in terms of the equipment that moves the work piece. This solution is therefore not particularly attractive on cost grounds, especially from a fixed cost point of view.
Patent EP 2281653 A1 discloses a method of friction welding of blades in a fan disk or a fan at the intake to an axial turbomachine. This patent focuses on the problem of the lack of control over the forging pressure at the extremities of the faying surfaces of the pieces to be welded, when the section of material below the faying surface decreases at too steep an angle. The method described is notable in that it provides for a first contact zone under the faying surface without any reduction in section, which is then followed by a second zone with the material tapering off. The welding process that is described therein is a linear friction welding process. It suggests that an orbital friction welding method can also be used, without specifying the conditions under which it can be used. As in the previous patent, this patent focuses on a linear friction welding process which necessitates expensive equipment.